Study of ordered structures of syndiotactic poly(methyl methacrylate) in solution and in the solid state

Abstract

Abstract From analysis of infrared spectra it was found that in syndiotactic ( s ) poly(methyl methacrylate) (PMMA) in solution, long s sequences contain an increased population of diads with a skeletal conformation tt (in the staggered approximation). Self‐aggregation of s ‐PMMA in solution leads to a further increase of the fraction of long s sequences in the extended chain conformation, and to an ordering of easter groups. When solid s ‐PMMA is isolated from a solution in which it exists in the aggregated state, these characteristics are preserved in the solid. The polymer appears partially crystalline by x‐ray scattering, and it exhibits fibrillar morphology under the electron microscope. Ordered structures of s ‐PMMA melt at temperatures about 150°C, while the presence of residual solvent decreases the temperature of melting. Solid s ‐PMMA obtained from solutions in which aggregation of the polymer does not take place, like s ‐PMMA which did not come into contact with solvent, contains a higher proportion of syndiotactic diads with a skeletal conformation tg ; these samples are amorphous and morphologically structureless. Analogies between the structure of ordered s ‐PMMA and the structure of the PMMA stereocomplex are also discussed.